You should go to Cuba for a holiday and take as many used tennis balls as you can to give away to the children or to give to hotel staff as tips. I couldn't believe it the first time I saw this - one guy had brought in about 100 balls - he wanted to give one of the maids a tip, so he held up a $1 US bill in one hand and a used tennis ball in the other and gave the maid a choice of getting either - and she wanted the tennis ball!!! I'm sure she had her own child to give it to. The children really love them and there is such a shortage of tennis balls on the island. On one tour in the mountains, we stopped at a school and this guy gave out about 30 balls to all the children - they all loved them so much. I'm sure there are many other holiday destinations where the same conditions exist. So save those balls and put them to good use!